Insights into the Stability and Activity of MIL-53(Fe) in Solar Photocatalytic Oxidation Processes in Water

MIL-53(Fe) is a metal organic framework that has been recently considered a heterogeneous photocatalyst candidate for the degradation of water pollutants under visible or solar radiation, though stability studies are rather scarce in the literature. In this work, MIL-53(Fe) was successfully synthesized by a solvothermal method and fully characterized by X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), N2 adsorption–desorption isotherm, Thermogravimetric analysis coupled with mass spectrometry (TGA-MS), UV-visible diffuse reflectance spectroscopy (DRS), elemental analysis and wavelength dispersive X-ray fluorescence (WDXRF). The effects of pH, temperature, solar radiation and the presence of oxidants (i.e., electron acceptors) such as ozone, persulfate and hydrogen peroxide on the stability of MIL-53(Fe) in water were investigated. The as-synthetized MIL-53(Fe) exhibited relatively good stability in water at pH 4 but suffered fast hydrolysis at alkaline conditions. At pH 4–5, temperature, radiation (solar and visible radiation) and oxidants exerted negative effect on the stability of the metal–organic framework (MOF) in water, resulting in non-negligible amounts of metal (iron) and linker (terephthalic acid, H2BDC) leached out from MIL-53(Fe). The photocatalytic activity of MIL-53(Fe) under simulated solar radiation was studied using phenol and metoprolol as target pollutants. MIL-53(Fe) on its own removed less than 10% of the pollutants after 3 h of irradiation, while in the presence of ozone, persulfate or hydrogen peroxide, complete elimination of pollutants was achieved within 2 h of exposure to radiation. However, the presence of oxidants and the formation of some reaction intermediates (e.g., short-chain carboxylic acids) accelerated MIL-53(Fe) decarboxylation. The findings of this work suggest that MIL-53(Fe) should not be recommended as a heterogeneous photocatalyst for water treatment before carrying out a careful evaluation of its stability under actual reaction conditions.

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Application of near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) in an in-situ analysis of the stability of the surface-supported metal-organic framework HKUST-1 in water, methanol and pyridine atmospheres

Journal of Electron Spectroscopy and Related Phenomena ◽

10.1016/j.elspec.2020.147042 ◽

2021 ◽

pp. 147042

Author(s):

Marit Kjærvik ◽

Paul M. Dietrich ◽

Andreas Thissen ◽

Jörg Radnik ◽

Alexei Nefedov ◽

...

Keyword(s):

Photoelectron Spectroscopy ◽

Ambient Pressure ◽

Metal Organic Framework ◽

In Situ Analysis ◽

X Ray ◽

Metal Organic ◽

The Stability ◽

Organic Framework ◽

Supported Metal

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Characterization of a Holmium 4,4′-Biphenyldicarboxylate Metal-Organic Framework and Its Potential as a Holmium Carrier System

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.17476 ◽

2020 ◽

Vol 20 (5) ◽

pp. 3019-3024 ◽

Cited By ~ 1

Author(s):

Juan P. Vizuet ◽

Abigail L. Lewis ◽

Gregory T. McCandless ◽

Kenneth J. Balkus

Keyword(s):

Metal Organic Framework ◽

X Ray Diffraction ◽

X Ray ◽

Metal Organic ◽

Solvent Molecules ◽

The Stability ◽

Adsorption Desorption ◽

Organic Linker ◽

Organic Framework

There is growing interest in Holmium carriers for radiotherapeutic applications. In this work, a holmium-based metal-organic framework (MOF) using the 4,4′-biphenyldicarboxylic acid (H2BPDC) linker was synthesized and characterized to explore its potential as a radiotherapeutic carrier. The 3D MOF [Ho(BPDC)2]·(CH3)2NH2 was characterized by single crystal X-ray diffraction, FTIR, TGA and PXRD. A challenge to overcome in lanthanide-based MOFs is the deformation or collapse of the framework that can occur after evacuation of the pores. This structure displays high thermal stability and no collapse was observed when the molecules confined in the pores were removed. The coordination around the holmium center (CN = 8) is the key to this stability since only the organic linker and no solvent molecules coordinate to the metallic center. The porosity of the material was confirmed by high-pressure carbon dioxide (CO2) adsorption–desorption analysis. The stability of the MOF, its holmium content (28 wt%) and its porosity are features that make this material a potential holmium carrier for radiotherapeutic applications.

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Synthesis and Structure of a Clathrated Two-Dimensional Metal-Organic Framework: [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2·H2O (L = Bis(1-pyrazinylethylidene)hydrazine)

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20080024 ◽

2008 ◽

Vol 73 (1) ◽

pp. 24-31

Author(s):

Dayu Wu ◽

Genhua Wu ◽

Wei Huang ◽

Zhuqing Wang

Keyword(s):

Metal Organic Framework ◽

Channel Structure ◽

Two Dimensional ◽

X Ray Diffraction ◽

Guest Molecules ◽

X Ray ◽

Square Planar ◽

Metal Organic ◽

Aqueous Meoh ◽

Organic Framework

The compound [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2 was obtained by the reaction of Cd(ClO4)2, bis(1-pyrazinylethylidene)hydrazine (L) and 4,4'-bipyridine in aqueous MeOH. Single-crystal X-ray diffraction has revealed its two-dimensional metal-organic framework. The 2-D layers superpose on each other, giving a channel structure. The square planar grids consist of two pairs of shared edges with Cd(II) ion and a 4,4'-bipyridine molecule each vertex and side, respectively. The square cavity has a dimension of 11.817 × 11.781 Å. Two guest molecules of bis(1-pyrazinylethylidene)hydrazine are clathrated in every hydrophobic host cavity, being further stabilized by π-π stacking and hydrogen bonding. The results suggest that the hydrazine molecules present in the network serve as structure-directing templates in the formation of crystal structures.

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Backbonding contributions to small molecule chemisorption in a metal–organic framework with open copper(i) centers

Chemical Science ◽

10.1039/d0sc06038k ◽

2021 ◽

Author(s):

Gregory M. Su ◽

Han Wang ◽

Brandon R. Barnett ◽

Jeffrey R. Long ◽

David Prendergast ◽

...

Keyword(s):

Fine Structure ◽

Small Molecule ◽

Metal Organic Framework ◽

X Ray ◽

Metal Site ◽

Absorption Fine ◽

Metal Organic ◽

X Ray Absorption ◽

Organic Framework

In situ near edge X-ray absorption fine structure spectroscopy directly probes unoccupied states associated with backbonding interactions between the open metal site in a metal–organic framework and various small molecule guests.

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